Storage and retrieval system with a motor current sensing to detect obstructions

ABSTRACT

An automatic warehouse system which allows an operator to sit at a fixed station and by placing punched cards into card readers and pressing a &#39;&#39;&#39;&#39;GO&#39;&#39;&#39;&#39; button can cause a fork to take one article from a pickup station into storage and to retrieve any other article from storage on its return trip and bring it to a point. Depending upon the information punched on the card, it can skip either the storage or the retrieval operation and perform the other or it can cause the fork to move an article from any rack in the warehouse to any other rack without returning to the pickup or set-down stations. In performing these movements in three dimensions, the system is provided with apparatus which recalculates the position of the fork every step of the way so as to eliminate any error that may occur, and stops, backs out or returns to the pickup station if it detects a full bin or other obstruction.

United States Patent Cotton et al.

is] 3,677,420 [451 July 18,1972

[54] STORAGE AND RETRIEVAL SYSTEM WITH A MOTOR CURRENT SENSING TO DETECT OBSTRUCTIONS [72] Inventors: Ronald K. Cotton, Rockledge, Fla; Barney O. Rae, Shorewood, Wis.

Related US. Application Data [60] Division of Ser. No. 670,094, Nov. 25, 1967, Pat. No. 3,537,602, which is a division of Ser. No. 498,326, Oct. 20, 1965, Pat. No. 3,504,245, Division of Ser. No. 7,889, Feb. 2, 1970, abandoned, which is a continuation of Ser. No. 198,210, Nov. 12, 1970.

3,076,566 2/ 1963 Dennis ..2 14/164 A 3,139,994 7/1964 Chosan. ....214/16.4 A 3,199,857 8/1965 Klamp ..318/47S X 3,232,455 2/1966 Fountain et al. ....214/16.4 A

R25,959 2/1966 Ranson ..3l8/474 X 3,389,814 6/1968 Lemelson..... ....214/16.4 A 3,402,836 8/1968 Debrey et al. ....214/16.4 A 3,531,002 9/1970 Lemelson ..214/16.4 A

Primary Examiner-Gerald M. Forlenza Assistant Examiner-Raymond B. Johnson Attorney-Hugh R. Rather [57] ABSTRACT An automatic warehouse system which allows an operator to sit at a fixed station and by placing punched cards into card readers and pressing a GO button can cause a fork to take one article from a pickup station into storage and to retrieve any other article from storage on its return trip and bring it to a point. Depending upon the information punched on the card, it can skip either the storage or the retrieval operation and perform the other or it can cause the fork to move an article from any rack in the warehouse to any other rack without returning to the pickup or set-down stations. In performing these movements in three dimensions, the system is provided with apparatus which recalculates the position of the fork every step of the way so as to eliminate any error that may occur, and stops, backs out or returns to the pickup station if it detects a full bin or other obstruction.

2 Claims, 20 Drawing Figures Patented July 18, 1972 I 3,677,420

17 Sheets-Shoot 2 DCI IC D-C- ER DCZ A c 448V. POWER SCLS RCLS TO TROLLEY MOTOR CONTROL Patented July 18, 1972 3,677,420

17 Sheets-Sheet 5 Patented July 18, 1972 3,677,420

17 Sheets-Shut 4 gigs we 2 s CARD READER NO.I

P25 P26 P27 PR8 m ma Pa; PR4

PROXIMITY READERS REGIHER A r I L Patented July 18, 1972 3,677,420

17 Sheets-Sheet 6 NOT Fla. 3 H65 FIG. 8

FIG.9 FIG. FIGJJ F|G.4 Flaw FIG-IO FIGJZ FIG-I10- Patented July 18, 1972 17 Sheets-Sheet 7 9 2 2 an MN on .m #m pm 3 g tum Qua

mlmQmob-mm Qua- a I .F a; h :26 85:35.53 m 3363 3 am mm Patented July 18, 1972 1') Shuts-Shut 9 LSM NLS ML Patented July 18, 1972 3,677,420

17 Sheets-Shoat 1O Pate nt ed July 18, 1972 l? Shuts-Sheet ll JOUhZOO QOFOE uQnIUQ 408F200 UQFOE )QJJOUF own All

17 Sheets-Sheet 12 Patented July 18, 1972 awn z w cw 2% fl w m w w w m P m w m m m B S B M T T B u m" n A A A d 4 5 \1 w N N a w; I 2 I Z M 0 4 .l a Z T E 5 w M R A 0. LI L L s z E f M F a D r 5 s A T n r A n f m D Y L T R C H 7 1 0 a, \l. 1 a/ m u Patented July 18, 1972 17 Sheets-Sheet 14 l 3 c c c c s s s s 8). w I 6 w w LLL www 851352 v a 323 m Patented July 18, 1972 3,677,420

17 Sheets-Sheet l5 zuo. sues 5R0. 8 3:5 F51 REV.

Patented July 18, 1972 17 Sheets-Sheet l6 STORE CYCLE u PRoGRAM 7 I CARD I BRIDGE-- SAME AS PR3 TROLLEY-- SAME AS PR2 HOIST SAME AS PR5 ROTATE--- SAME AS PRI NO MOTION & PRoGRAM 7A 1 CARD BRlDGE-- 4 (HOME) TROLLEY- X34 (HOME) HOIST 9 (ROTATE) ROTATE-- SAME AS PRI TROLLEY TO HOME PROGRAM 8 l CARD BRIDGE SAME AS PR3 TROLLEY-- SAME AS PR2 HOIST SAME AS PR5 ROTATE SAME AS PRI NO MOTION n- PRoGRAM aAl CARD BRIDGE 4 (HOME) TROLLEY 34(HOME) HOIST 9 (ROTATE) ROTATE-- X2(MIDDLE) ROTATE TO CENTER I1 PRoGRAM 9 l CARD I BRIDGE SAME AS PR3 TROLLEY- SAME AS PR2 HOIST SAME AS PR5 ROTATE SAME AS PRI NO MOTION n PRoGRAM 9A| CARD BRIDGE 4 (HOME) TROLLEY-- 34 (HOME) HOIST X6 (PICK-UP) ROTATE-- 2 (MIDDLE) SET LOAO DOWN 8 CLEAR SYSTEM uu PROGRAM I0 I CARD I BRIDGE SAME AS PR3 TROLLEY- NO CODE HOIST SAME AS PR5 ROTATE SAME AS PRI u PROGRAM CARD 1 BRIDGE 4 (HOME) TROLLEY- 34 (HOME) HOIST X9 (ROTATE) ROTATE- X3 (NORTH) HOIST TO ROTATE POSITION B ROTATE -u r PROGRAM 2 I CARD BRIDGE SAME AS PRI TROLLEY- X28 (STORE) HOIST SAME AS PRI ROTATE SAME AS PRI TROLLEY TO STORE AISLE --un PRoGRAM 3 I cARo BRIDGE X20 (STORE) TROLLEY-- SAME AS PR2 HOIST X7(STORE) ROTATE-- SAME AS PRI BRIDGE B HOIST TO STORE POSITION -uu PROGRAM 4 CARD BRIDGE SAME AS PR3 TROLLEY- SAME AS PR2 BCTD HOIST SAME AS PR3 ROTATE SAME AS PRI MOVE TROLLEY INTO BIN 41 PRoGRAM 5 1 CARDI BRIDGE SAME AS PR3 TROLLEY- SAME AS PR2 BCTO HOIST XSII POS.BELOW PR3) ROTATE SAME AS PRI LOWER HOIST B BACK INTO AISLE n PROGRAM 5A 1 CARD BRIDGE SAME As PR3 TROLLEY-- SAME As PRzacTo HOIST SAME AS PR3 ROTATE- SAME AS PRI (BIN FULL) BACK INTO AISLE u PROGRAM 6 CARD BRIDGE SAME AS PR3 TROLLEY SAME AS PR2 HOIST-- SAME AS PR5 ROTATE SAME AS PRI NO MOTION 0- PRoGRAM GA CARD BRIDGE X4 (HOME) TROLLEY- SAME AS PR2 HOIST X9 I ROTATE) ROTATE SAME AS PRI BRIDGE TO HOME 8 TO ROTATE POSITION HOIST CHECK AISLE 8 ROTATE BRIDGE N0 coDE g%EY- n 4 gggRlEVE) PROGRAM I6 1 CARD 2 A BRIDGE x4 (HOME) ROT TE No CODE -TRoI LEY- SAME AS PRIo CHECK AISLE a ROTATE H0lST--- x9 (ROTATE) PROGRAM H I CARD 2 ROTATE SAME AS PRIIB $33 x E PS BRIDGE,IIoIsTB ROTATE (HOME) LLEY--- SAM PR 2 I I AIE X 22:32: SIMRIS P W B IDGE B RoI r o %EPTRRIIEVE X9 (SET DOWN POSITION(SAME AISLE-SAME sIDE) S831 Q I I l BRIDGE 4 (HOME) I g PROGRAM |7Al CARD 2 x $3295.? 355%??? SEI'IZMI 3312? 2 $8555 TROLL a HOlST-- SAME AS PRIG IHHI PROGRAM IIBI CARD 2 I TATE Z E v 9 gagkg AISLE) TROLLEY TO SET DOWN #2 ADPs 'I Y '9 ((ROTATEA PROGRAM l CARD 2 ROTATE XI (SOUTH) BRIDGE SAME AS PRIG BRIDGE TO MIDDLE AISLE TROLLEY- SAME AS PRIB TROLLEY a HOIST T0 ROTATE HOIST xs {1 l 2 ROTATE SAME AS PRIT $281 22% :2 :2) I owER LOAD ONTO STATION "om SAME As PR PROGRAM IBAI cARD 2 ROTATE SAME AS PR II I BRIDGE SAME AS PRIG No MOTION I I Ev- 22MB AS PRIG I} PROGRAM 12A] CARD 2 ROTATE- SAME AS PRIIA 2252- gAJE gg gR'o owER LOAD ONTO STATION L Y- 0'51- 9 "1] .2- PROGRAM I9 I CARD 2 ROTATE SAME AS PR IIA BRIDGE SAME AS PRIG TROLLEY TO RETRIEVE AISLE Iggyfg'fi fi' III PROGRAM I281 CARD 2 22%? ssrsvmfigz BRIDGE SAME AS PRIIB I FORKS TO ROTATE P0 m0 HOISTV SAME AS PRIIB ME AS PR"; ROUTE SAME'AS (?L L EY- 2AM: AS PRIS TROLLEY T0 RETRIEVE AISLE o s-r x9 (ROTATE) ROTATE. SAME AS PRI7A PROGRAM l CARD 2 AFTER TIME DELAY-- RAISE BRIDGE x30 FORKS T0 ROTATE POSITION Patented July 18, 1972 3,677,420

17 Sheets-Sheet l7 -1]U" PROGRAM l5 1 CARD 2 BRIDGE SAME AS PR l3 TROLLEY SAME AS PRIO & CTD HOIST XI3(I POSABOVE PRIS) ROTATE SAME AS PRIIB RAISE HOIST 8 BACK INTO AISLE fill- PROGRAM I0 I CARD 2 '1 PROGRAM llAI CARD 2 TROLLEY TO SET DOWN #l TROLLEY- SAME AS PRIo I Ho's]. x'z l]l} PROGRAM 20l CARD 2 v mGE SAME AS PRIG ROTATE SAME AS PRIIB TROLLEY" X34 BRIDGE GI HOIST T0 RETRIEVE HOIST SAME AS P 5m ROTATE SAME AS PRIS 'FR0GRAM I4 I CARD 2 T N amu e SAME As Pm: TROLLEY TO HOME POSI 0 TROLLEY-.- SAME AS PRIOBICTD HO|ST-- SAME AS PRI3 PROGRAM CARD 2 I BRIDGE SAME AS PRIG SAME As TROLLEY SAME AS vI-"Rzo MovE TROLLEY INTO BIN HOIST xs (HOME) ROTATE SAME AS PRIS LOWER FORKS TO PICK-UP ELEVATION 8 CLEAR SYSTEM STORAGE AND RETRIEVAL SYSTEM WITH A MOTOR CURRENT SENSING TO DETECT OBSTRUCTIONS CROSS REFERENCES TO RELATED APPLICATION This application is a first division of our copending application Ser. No. 670,094, filed Nov. 25, 1967, now US. Pat. No. 3,537,602, dated Nov. 3, 1970, which is a division of our original application Ser. No. 498,326, filed Oct. 20, 1965, now US. Pat. No. 3,504,245, dated Mar. 31, 1970. A second division of such copending application is our Ser. No. 7,889, filed Feb. 2, 1970, now abandoned and replaced by our copending continuation Ser. No. 198,210, filed Nov. 12, 1970.

BACKGROUND OF INVENTION This invention relates to automatic storage and retrieval systems and more particularly to an electrical system for controlling multiple coordinate movements in three dimensions of a crane or the like to place articles in storage racks or bins of a warehouse and to remove articles therefrom under the control of punched cards or the like information bearing media.

While not limited thereto, the invention is especially applicable to control of the left or right and forward or back trolley and bridge movements, respectively, and the vertical and rotary hoist and fork movements, respectively, of a stacker crane.

Cranes of this type have heretofore been operated under manual control and under partial automatic control. Under manual control, the operator rides the fork so. that he can see where it is going and from individual hand levers first runs the trolley in a cross aisle along the bridge to a point opposite the desired long aisle and rotates the fork, which may carry a twenty foot long bundle of metal bar stock, so that the load will fit into the long aisle. The operator then operates additional hand levers to run the bridge whereby to move the load down the aisle and to run the hoist to raise the load adjacent the desired rack. The operator then operates the trolley and hoist levers again to move the load over the rack, to lower the load onto the rack and to reverse the trolley back into the aisle. Under partial automatic control, a keyboard, dial or the like has been used to insert directive information into a control system which then controls the movements of the loadcarrying fork. But these partial automatic control systems have been constructed and arranged on a counting basis so that after each operation, storing or retrieving as the case may be, the fork must return to the starting point before it can be sent out again on another errand. In these known systems, the directive information was put in initially and correct operation depended on its remaining sequentially accurate as stepping switches or the like were used. Thus, any error that might get in would give the device a false lead.

SUMMARY OF THE INVENTION This invention relates to an automation system which allows the operator to sit at a fixed station and by merely placing punched cards (or equivalent information bearing media) into card readers or the like and pressing a GO button can cause the fork to take one article from the pickup station into storage and to retrieve any other article from storage and bring it to a selected set-down station before returning to the starting point or it can skip either the storage or retrieval operation. Or, depending, upon the infonnation punched on the cards, the system can cause the fork to move an article from any rack in the warehouse to any other empty rack without returning to the pickup or set-down stations. If it senses a full rack or other obstruction, it will stop, back out into the aisle and return to the pickup station. The invention has been devised to do this with the utmost reliability as will hereinafter appear.

An object of the invention is to provide an improved automation system for multiple coordinate motions control having .obstruction detection means.

A more specific object of the invention is to provide an improved three dimensional motions control system of the aforesaid type which is continuously self-checking to avoid error.

Another specific object of the invention is to provide a motions control system of the aforesaid type which is constructed to provide better accuracy.

Another specific object of the invention is to provide a motions control system of the aforesaid type which recalculates its position every step of the way so that the system eliminates errors and always knows where it is.

Another specific object of the invention is to provide a motions control system of the aforesaid type which does the job faster because it can perform a second operation without coming to the home or starting point after the previous operation.

Another specific object of the invention is to provide a motions control system of the aforesaid type employing fully digital control which is especially adapted for sensing the direction in which it must move, for sensing how far away it is from its destination and for sensing slowdown points.

Another specific object of the invention is to provide an improved multiple coordinate, three dimensional control system for a stacker crane having optimum flexibility in that it is capable of performing a large number of functions.

A further specific object of the invention is to provide an improved numerical, direct static logic system for controlling interlocked movements of a multiple coordinate motions stacker crane from punched cards or similar digital code bearing media.

Other objects and advantages of the invention will hereinafter appear.

According to the invention, there is provided a direct static logic system for controlling a stacker crane, direct meaning that a positive input to a logic element produces a positive output and a zero input produces a zero output and no signal inversion takes place in any of the logic elements except the NOT logic element which purposely inverts the voltage.

The heart of the system is a digital computer of the binary code subtracting type which computes the directions and the distances every step of the way and the slowdown points at the proper times rather than relying on a less reliable sequencing scheme. This computer subtracts the desired-position indicative binary code from the actual-position indicative binary code for each of the bridge, the trolley and hoist and provides both a direction indicative signal at one of two possible out puts and a distance indicative difference binary code for controlling the respective motions. These subtractions are performed at predetermined steps along the way when the actualposition indicative binary codes are read so that any error which might have occurred at one point is completely eliminated when a new reading is taken and a new subtraction made. The desired-position indicative binary codes are obtained from punched cards by card readers and applied directly to the subtractor. Two card readers are used, one for storage codes and the other for retrieval codes to allow the crane to go from any place to any other place. The actualposition indicative binary codes are read from sets of magnetic code bars by proximity readers moving with the bridge, trolley and hoist, respectively, these sets of code bars being mounted along their respective paths of travel. Although difference binary codes of large magnitude are obtainable, since seven, six and six bit binary codes are used for the bridge, trolley and hoist, respectively, all codes larger than slowdown values function in the same way in conjunction with the direction indicative signal to cause continuous base speed operation whereas small difference binary codes such as equivalent decimal values of 3, 2 and l for the bridge and 2 and 1 for each of the trolley and hoist initiate slowdown action preparatory to stopping at zero difference, it being recognized that these small difference binary codes indicate that the moving device, as the case may be, is approaching its desired destination.

Rotary motion of the mast which mounts the article-supporting fork does not require computer control in the illustrated embodiment since its movements for warehousing application are relatively simple. That is, the fork has only three positions, a middle or westwardly directed position for loading and unloading purposes and north and south positions for the racks on opposite sides of the long aisle. The rotary position indicative codes, which are one hole codes for north or south or middle, are obtained from the punched cards by the card readers and are applied directly to the rotate motor control, the rotation being stopped at the proper position by limit switches.

The system is also provided with means for performing auxiliary functions including bypassing the storing or retrieving cycle under the control of a bypass card but allowing the other unbypassed cycle to take place; detecting a full rack or bin or other obstruction and returning the load to the pickup station; at the end of a storing cycle when the empty fork is in the long aisle adjacent the just-filled storage rack, determining whether the article to be retrieved is in a new aisle or side and if so, selecting another binary code program from the punched card which will cause movement of the bridge first to a cross aisle to allow shifting of the trolley or rotation of the fork; in conjunction with the above new aisle or side determination, selecting the nearest cross aisle for trolley shifting or fork rotation by choosing between two alternatives in the selected other binary code program, one of which will route the bridge back to the west (home) cross aisle when the just-filled storage bin is within a first range of bridge positions and the other of which will route the bridge to the middle cross aisle when the just-filled storage bin is beyond said range in the remaining bridge positions, it being assumed, of course, that these ranges of bridge positions are nearest the respective cross aisles; and selecting under manual control either one of two set-down stations to which the retrieved article is to be brought by selecting one of two retrieval programs from the punched card. Means for performing other particular auxiliary functions such as interlocks, lockouts, restrictions on certain movements, preset conditions, etc., will become apparent as the description proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages of the invention and the manner of obtaining them will best be understood by reference to the following description of an embodiment of an automatic storage and retrieval system taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective end view of a warehouse schematically showing three bays of racks or bins and the stacker crane installed therein;

FIG. 2 is a top plan view of an exemplary warehouse schematically showing a multiplicity of rows of racks or bins separated by eight long aisles and two cross aisles and a stacker crane resting in the west-end cross aisle;

FIGS. 3 through 14 are circuit diagrams schematically showing the automatic storage and retrieval system;

FIGS. 15 and 16 are circuit diagrams showing details of a binary code subtractor shown as a rectangle in the system of FIGS. 3-14;

FIG. 17 on sheet 14 shows details of a signal converter used in FIG. 15;

FIGS. 18 and 19 diagrammatically show the sequential operational program steps for the storage and retrieval cycles, respectively, of the system of FIGS. 1-16, including selectable alternate program steps; and

FIG. 20 on sheet 6 is a block diagram showing how the circuits of FIGS. 3-14 are assembled.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Refcrrin g to FIG. 1, the warehouse shown therein comprises a pair of side tracks or bridge rails 1 and 2, one along each side of the warehouse near the top, on which a stacker crane 3 is supported and along which it rolls the length of the warehouse. The bays 4 of racks or bins in which articles are stored stand on the floor of the warehouse. As shown schematically in FIG. 1, each bay 4 comprises a center frame 5 and horizontal rows and vertical columns of bins 6 supported on opposite sides of the center frame so that they are accessible from the long aisles 7 which run between the bays. Alternatively, racks may be used instead of bins which would consist of spaced apart steel beams in rows and columns projecting in cantilever fashion in opposite directions from main frame 5. As will be apparent, such racks could support elongated articles such as metal bar stock including angle irons, rods, etc., in groups of bundles which would span two or more of the steel beams. While only three enlarged bays of storage bins are shown in FIG. 1 for clarity of illustration it will be apparent that a larger number thereof is normally used in a warehouse as shown in the top view of FIG. 2.

As shown in FIG. 1, stacker crane 3 comprises a bridge 8 spanning the warehouse and supported at its opposite ends on side rails 1 and 2. The ends of the bridge are provided with wheels (not shown) driven by an electric motor drive in known manner to afford running of the bridge the length of the warehouse.

The stacker crane also comprises a trolley 9 which is provided with wheels (not shown) driven by an electric motor drive in known manner to afford running of the trolley the length of the bridge across the warehouse. For this purpose, the bridge is provided with suitable rails (not shown) for the trolley to roll along. The trolley is additionally provided with a suitable ring gear structure or the like (not shown) and a rotate motor drive for rotating a mast l0 suspended therefrom.

The stacker crane further comprises a hoist 11 for moving a fork F or other article supporting device up and down along mast 10 so as to position the article opposite any bin in a column thereof. Magnetic code bars 12 are mounted in predetermined spaced apart relation upwardly along mast 10 and have binary codes starting with 3 at the lower end to be read by a hoist proximity reader (hereinafter described and shown in FIG. 5) to control the positioning of the fork relative to the bins or racks in which articles are to be stored, binary codes 2 and 1 being used for slowdown of the hoist.

A warehouse having a multiplicity of rack bays 4 is shown in FIG. 2, these bays being separated by long aisles 7 and a home or west cross aisle and a center cross aisle, shown in top plan view. In the example of warehouse shown in FIG. 2, there are eight long aisles providing seven full bays with their bins backto-back and two half bays, there being one such half bay facing each of the first and eighth long aisle with its back against the side wall of the warehouse.

The home cross aisle at the west end of the warehouse is provided for loading and unloading articles onto and from the fork. For this purpose, there are provided an entry conveyor EC leading eastwardly to a pickup station in the home cross aisle and a pair of exit conveyors XC1 and XCZ leading westwardly away from respective set-down stations Nos. 1 and 2 in the home cross aisle. For exemplary purposes, the pickup station has been located at the trolley binary code position having a decimal equivalent of 34 (hereinafter called binary code position 34) and the set-down stations Nos. 1 and 2 have been located at trolley binary code positions 9 and 19, respectively, the trolley positions having binary codes starting with 3 at the south end of the bridge to the north end thereof. The entry conveyor is arranged to move an article directly onto the fork when the latter is positioned slightly below the top of the entry conveyor at hoist binary position 6. In a similar manner, each exit conveyor is arranged to move an article directly off the fork after the latter deposits an article thereon in response to lowering of the hoist to binary code position 6.

The trolley and bridge are also provided with positioning control devices. As shown schematically in FIG. 2, magnetic code bars 13 are mounted in predetermined spaced apart relation along the bridge and have binary codes starting with 3 at 

1. In a control system for a transporter that is adapted to store articles in a storage structure having individual article receiving compartments arranged along an aisle along which the transporter is adapted to move and for selecting articles therefrom and delivering them to a delivery station, the improvement comprising: binary code input means operable for inserting into the system desired compartment indicative codes; program control means for controlling said system; means for initiating operation of the system; motor control means including a motor means; control means operable upon initiation of operation of the system for causing said program control means to operate said motor control means through a store cycle to cause the transporter to convey an article in accordance with said binary codes to the desired compartment and for moving it into the compartment, and through a return cycle to cause the transporter to return to its home station, and through a retrieve cycle to cause the transporter to pick up an article from a desired compartment and deliver it to a delivery station; and obstruction detection means for controlling the movement of the transporter comprising: means in said motor control means operable when the article that is being conveyed or its transporter whether empty or full encounters an obstruction for causing an increase in motor current from its normal running value; means for sensing said increase in current; and means responsive to said sensing means for interrupting the store cycle and causing switching of said program control means to said return cycle to return the transporter to its home station.
 2. In a control system for a stacker crane that is adapted to store articles in article supporting racks having individual article receiving bins arranged along an aisle along which the stacker crane is adapted to move, the improvement comprising: binary code input controllable by an operator for inserting into the system desired bin indicative codes constituting a store cycle and home station indicative codes constituting a return cycle; program control means for controlling said system; means for initiating operation of the system; control means responsive to said initiation of operation of the system for controlling said program control means through a store cycle to cause the stacker crane to pick up an article and to carry it in accordance with and under the control of said binary codes to the desired bin and to deposit it in said bin; said control means being further operable following deposit of an article in a bin for controlling said program control means through a return cycle for returning the crane empty to itS home station; said control means comprising: binary coded means mounted along coordinate paths like the coordinate paths of movement of the stacker crane and being indicative of actual positions thereof; means movable in synchronism with the stacker crane for extracting actual-position indicative codes from said binary coded means at predetermined spaced points as the stacker crane moves; means for comparing the actual-position indicative code with the inserted code to obtain a difference code each time an actual-position indicative code is extracted; means responsive to said comparison for providing directional output signals indicative of the polarities of the difference codes, that is, indicative of whether the difference code is plus or minus; motor control means including a motor means operable to cause the stacker crane to be driven in the coordinate movements in a predetermined order in accordance with the last provided directional signal and the last obtained difference code; said motor control means comprising travel, hoist and lateral motor controls for moving the stacker crane along the aisle, for hoisting the article to the level of the desired bin, and for moving the article laterally into the bin, lowering it for deposit therein, and retracting the article carrier from the bin; said program control means comprising means for controlling said motor controls and said motor means to effect these movements in a predetermined order; and full bin detector means comprising: a motor current responsive relay operable to sense increase in the lateral motor control current from the normal value which it has when slow lateral motion is taking place when the article being stored abuts an article already in the bin and means responsive to said relay to cause switching of said program control means to a return cycle to control return of the first mentioned article back to the home station. 